So far, I've mostly played the game as Carthage, so most of my ideas will be based on those experiences. I've started an 1.02 and more recently a 1.03 game, though I've played 1.01 as the Belgae and Rome too so far. But, basically, all factions in the underdeveloped western Mediterranean. I imagine (and hope) that the eastern theatre will play somewhat different But, I'm reflecting on my experiences, so I overlook things in my series of ideas, don't hesitate to point that out to me. I feel I like discussing this game

From what I understand so far, I see one quirk in how the trade-mechanic works. Being the mercantile republic Carthage is, increasing the trade range of Tunes/Carthage is actually not beneficial. Let me explain. Because you can not by 3th party resources and resell them to other factions, the main business a mercantile republic can do in this game is exporting it's own trade-goods to other factions (and trading internally offcourse), thus conquering foreign markets with our goods (in which Trade Acumen plays the leading role). This is handled by a chance-based formula, so that trades fluctuate. So far, so good. Now, if I upgraded my harbour in Tunes and consequently enlarge my Trade Range, I mostly see negative effects. Why is that? Mostly because trades happen if a region is lacking a resource and it consequently goes looking for it. So, increasing my Trade Range only increases the change of a Tunes import happening externally. This is because more regions (mainly external) with the necessary resource, say Flax as an example, come within range. Thus the chance increases of the trade happening external. A higher Trade Range doesn't improve my chances of exporting, even though a lot more regions are now within my range. Even though I can export to Italia, it's not happening because I'm not in their Trade Range (with some exceptions offcourse). It would make a lot more sense if a trade can happen if either the importer or the exporter are within range of eachother, certainly in the case of a mercantile faction. After all, we assume my merchants actively seek out trading opportunities! After all, I'm getting diplomatically punished for being a mercantile power, why not let me reap the benefits as well?

Now I've come to think of it, how does the cooperation diplomatic option influence all of this? Offcourse, I see some room for more diplomatic options surrounding trade as well. Trade-bans on certain factions as well. I have a feeling that this might be historically correct as well, though somebody else might know more about this.

The advantage of increasing your trade range is yes, you are more likely to be able to import goods. If its needed this drops the import price from 3* base value to base value, in addition its then available for use for bonus production.

This is seriously good news for your economy

The only time to be careful about expanding trade range is if (a) you have low acumen and (b) are currently trading for that good internally. In this case look at the decision carefully, some elements stress acumen, other options range

Co-operation reduces the barrier to external trade - there is usually a bias to internal trade that can be overcome by better trade acumen or luck. Its one reason why if you are a trading nation you see the malus to co-op/ally such as 'flood our markets with your goods' - the AI suspects (rightly) you are going to get very rich at their cost.

Let's say first you have a trade range of 5. Your region needs an import and can get it from internal provinces at ranges 3 & 4. No external regions with the resource are available. The trade happens exclusively internal. Then, the trade range gets upgraded to 7. Now there are another 2 external regions with the needed resources within range, admittingly with lower trade acumen, at ranges 6 & 7. Because a trade gets alocated based on probability, some turns, from now on, the trade will take place with an external province, too. Thus, upgrading a trade range actually works against you as well. It's only beneficial when a needed resource is out of range, but that applies to any faction, be it mercantile or not.

So, that is why I'm pleading to use the exporter's Trade Range, at least in the case of mercantile factions. So that upgrading the Trade Range works beneficiary and that it upgrades the chances of an export happening. Right now, for an export to happen, you need to wait before your regions come within range of the other faction's regions. That's not how I imagine mercantile factions work. Their merchants are the ones seeking out trade opportunities, aggressively. Now, I can upgrade and have all the resources I want in Carthage, if, for example, the Italic regions don't improve their Trade Range, no exports happen. The same logic applies for internal trade as well. I can have all the buildings, implicating extensive trade networks, if we don't get a decent harbour upgrade in for example Insani, Sardegna, no trade will take place. I feel Carthage's tradesmen are a bit powerless. They have to wait for the outside world to come to them.

Thanks a lot for the clarification, understanding and acknowledging to keep improving the game. That was a short post with a lot of information I have now doubt will get better and better. The community will probably keep informing what areas can be improved (according to us ). I will certainly keep contributing as well